• 한국재료학회지
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• 제7권6호
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• pp.479-483
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• 1997

Sol-gel법으로 제작한 여러 종류의 Zr/Ti비율을 갖고 있는 PZT박막의 전지적 특성과 신뢰성 특성을 상부 백금 전극을 sputtering으로 증착하고 Ar 기체로 반응성 이온 식각(RIE)방법으로 패턴을 형성한 후 열처리온도의 변화에 따라 조사하였다. Hysteresis loop특성을 되찾게 하였다. Zr/Ti 비율이 감소함에 따라 voltage shift가 증가하였으며 internal field가 없어지는 열처리 온도가 증가하였다. Zr/Ti비율이 감소함에 따라 초기 잔류 분극은 증가하였으나 switching 횟수가 증가됨에 따라 잔류 분극이 급속히 감소하였다.

• 대한금속재료학회지
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• 제46권2호
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• pp.53-57
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• 2008

This study examined the role of excess free volume on the corrosion resistance of an amorphous alloy. Corrosion behaviors were monitored on the amorphous alloys, of which amount of free volume was controlled via the isothermal annealing below the glass transition temperature, using immersion tests and potentiodynamic polarization tests in HCl aqueous solutions. It was found that the corrosion resistance of the amorphous alloy is improved by reducing the amount of excess free volume. The possible reason explaining the experimental result was discussed from the viewpoint of the internal energy associated with the annihilation of excess free volume.

• 대한치과기공학회지
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• 제41권4호
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• pp.255-262
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• 2019

Purpose: Recently, the production technology of dental prosthesis using 3D Printer workpeices has been developed. However, the lack of information on the work processes and casting techniques of materials for 3D printing casting is expected to require research. Therefore, in this study, we intend to cast a Dental DLP 3D Printer workpiece, which is being commercialized, to identify its appearance and internal clearance, and to observe its castability. Methods: Castability of the 3D Printer workpiece was evaluated. The specimen is prepared in a cylindrical shape and in a 1 mm thick coping shape. The control specimen is made of wax and the experimental specimen is made of resin using two types of 3D printers. After casting, the appearance of the casting body was observed and the internal clearance of the coping was measured. Results: RP1 and RP2, cylindrical specimens, were partially cast or fin. When coping-type specimens were measured before casting, the internal clearance of PE2 was more accurate than that of PC and PE1. When coping-type specimens were measured after casting, CE1 was the most accurate in occlusal clearance and CE2n was the most accurate in axial clearance. Conclusion: 1. Exterior observations of the casting body indicated casting defects and fins. 2. Internal clearance observations show that the occlusal clearance of the castings is larger after casting, and the axial clearance of the castings is smaller after casting. 3. It is judged that the RP2 specimen is more likely to be applied for casting than the RP1 specimen.

• 한국화재소방학회논문지
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• 제30권2호
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• pp.7-18
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• 2016

본 연구는 주택이나 창고 등의 내부 마감재로 사용하는 합성 목재의 연소 독성평가에 관한 것으로 SEM, 콘 칼로리미터, FTIR를 활용해 집성판, MDF, 미송합판, 코어합판, 나왕 방부목 5종의 재료별 연소가스 독성을 실험 및 분석하였다. 각 재료별 독성특성 중 나왕 방부목에서 이산화탄소($CO_2$)의 치사농도인 100,000 ppm을 2.5배 초과하는 256,965 ppm, 이산화황($SO_2$)의 치사농도인 400 ppm의 3.6배를 초과하는 1,475 ppm이 검출되었다. 집성판은 이산화질소($NO_2$)가 1,569 ppm으로 치사농도인 250 ppm의 6배가 측정되었고, 암모니아($NH_3$)는 MDF에서 치사농도 값인 750 ppm 대비 795 ppm이 측정되었다. 따라서 대부분의 건축 재료에서 인체에 치명적인 가스가 발생되는 것을 확인하였고, 향후 건축 재료의 위해성을 평가하기 위한 기초데이터로 활용하고자 한다.

• 대한한방내과학회지
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• 제30권4호
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• pp.732-745
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• 2009

Objectives : This study analyzed the contents of research papers of complementary and alternative medicine (CAM) concerning chronic obstructive pulmonary disease (COPD) published in PubMed during the last 5 years. This study was conducted to help clinical studies for treating COPD with Oriental medicine. Materials and Methods : We inspected 31 theses and scrutinized their objectives, periods, participants, materials and methods, methods of assessment, results and Jadad score. Results : The treatments in the studies were supplements, physical training, acupuncture, acu-TENS, Bojungikgi-tang (Buzhongyiqi-tang), counseling, breathing training, osteopathic manipulative treatment, reflexology, and distractive auditory stimuli. The aims of treatment were improvement of exercise capacity, lung function, quality of life, oxidative status, nutrient status, systemic inflammation, and cessation of smoking. The median for treatment period of study was 8 weeks, the median number of participants was 35 and the differences between mean $FEV_1$ from groups were less than 10% in 22 studies. The methods of assessment were lung function test, exercise capacity test, muscle strength test, questionnaire of QoL, laboratory studies, and measurement of nutrient state. The mean of Jadad score was $2.4\;{\pm}\;1.03$, and 24 treatment were assessed as effective. Conclusion : Recent CAM studies of COPD have focused on various topics in alternative and complementary medicine, and it is necessary to provide objective studies for treatment of this disease with Oriental medicines.

• 대한한방내과학회지
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• 제31권3호
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• pp.500-512
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• 2010

Objectives : This study was designed to investigate the effects of SuJeom-san(SJS) extract in rats with caerulein-induced acute pancreatitis (AP). Methods : We examined changes of pancreatic weight, histological, immunohistochemical and gene expression of cyclooxygenase (COX-2). Thirty-six adult male Sprague-Dawley rats were divided into six groups as follow: normal(Nor), caerulein-induced (Con), caerulein + cefotaxime sodium(CT), caerulein + SJS 3 mg/kg(SJSA), caerulein + SJS 6 mg/kg(SJSB) and caerulein + SJS 12 mg/kg(SJSC) groups. Pancreatic tissues of rats from all groups were removed for histological observation and light, and electron microscopic examination. Platelet activating factor(PAF) and Interleukin-6(IL-6) levels were determined spectrophotometrically. Results : The ratio of pancreas/body weight was significantly(p<0.05) increased in the Con compared with Nor, but significantly(p<0.05) decreased in SJSA, SJSB, SJSC and CT groups compared with Con. Caerulein administration significantly increased(p<0.05) the levels of amylase, but SJSA, SJSB, SJSC and CT significantly(p<0.05) reduced the levels of these enzymes. The levels of platelet activating factor(PAF) increased in Con compared with Nor, but decreased in SJSA, SJSB, SJSC and CT groups compared with Con. Interleukin-6(IL-6) levels increased significantly in all groups compared to Nor at 6 hrs, but significantly(p<0.05) reduced in SJSA, SJSB, SJSC and CT groups compared with Con at 24 hrs. The levels of tumor necrosis factor(TNF)-${\alpha}$ levels increased in all groups compared to Nor at 6 hrs, but significantly(p<0.05) reduced in SJSA, SJSB, SJSC and CT groups compared with Con at 24 hrs. The COX-2 positive materials were observed in the pancreas of the Con, but these positive materials were decreased in the SJS extract treatment group. Conclusion : SJS is potentially capable of limiting pancreatic damage during AP by restoring the fine structure of acinar cells and tissue; therefore, we conclude that SJS may have beneficial effects in the treatment of caerulein-induced AP.

• Asian Pacific Journal of Cancer Prevention
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• 제15권12호
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• pp.4915-4918
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• 2014

Background and Aims: Advances in the treatment of cervical cancer over the last decade have predominantly involved the development of genes directed at molecular targets. Gene therapy is recognized to be a novel method for the treatment of cervical cancer. Genes can be administered into target cells via nanocarriers. This study aimed to develop systemically administrable nano-vectors. Floate (Fa) containing gene loaded nanoparticles (NPs) could target HeLa human cervical cancer cells through combination with receptors on the cells to increase the nuclear uptake of genetic materials. Methods: Fa was linked onto Poly (ethylene glycol)-b-poly (D, L-lactide) (PEG-PLA) to form Fa-PEG-PLA, and the resulting material was used to load plasmids of enhanced green fluorescence protein (pEGFP) to obtain gene loaded nanoparticles (Fa-NPs/DNA). Physical-chemical characteristics, in vitro release and cytotoxicity of Fa-NPs/DNA were evaluated. The in vitro transfection efficiency of Fa-NPs/DNA was evaluated in HeLa cells and human umbilical vein endothelial cells (HUVEC). PEG-PLA without Fa was used to load pEGFP from NPs/DNA as a control. Results: Fa-NPs/DNA has a particle size of 183 nm and a gene loading quantity of 92%. After 72h of transfection, Fa-NPs/DNA displayed over 20% higher transfection efficiency than NPs/DNA and 40% higher than naked DNA in HeLa cells. However, in HUVECs, no significant difference appeared between Fa-NPs/DNA and NPs/DNA. Conclusions: Fa-PEG-PLA NPs could function as excellent materials for gene loading. This nano-approach could be used as tumor cell targeted medicine for the treatment of cervical cancer.

• 한국재료학회지
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• 제27권1호
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• pp.48-52
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• 2017

In this study, we used I-V spectroscopy, photoconductivity (PC) yield and internal photoemission (IPE) yield using IPE spectroscopy to characterize the Schottky barrier heights (SBH) at insulator-semiconductor interfaces of Pt/$HfO_2$/p-type Si metal-insulator-semiconductor (MIS) capacitors. The leakage current characteristics of the MIS capacitor were analyzed according to the J-V and C-V curves. The leakage current behavior of the capacitors, which depends on the applied electric field, can be described using the Poole-Frenkel (P-F) emission, trap assisted tunneling (TAT), and direct tunneling (DT) models. The leakage current transport mechanism is controlled by the trap level energy depth of $HfO_2$. In order to further study the SBH and the electronic tunneling mechanism, the internal photoemission (IPE) yield was measured and analyzed. We obtained the SBH values of the Pt/$HfO_2$/p-type Si for use in Fowler plots in the square and cubic root IPE yield spectra curves. At the Pt/$HfO_2$/p-type Si interface, the SBH difference, which depends on the electrical potential, is related to (1) the work function (WF) difference and between the Pt and p-type Si and (2) the sub-gap defect state features (density and energy) in the given dielectric.

• Tuberculosis and Respiratory Diseases
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• 제52권2호
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• pp.174-178
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• 2002

기침 및 호흡곤란 주소로 내원한 43세 남자 환자에서 흉부 전산화 단층촬영 및 기관지경하 생검으로 다른 장기의 침범 없이 폐에만 국한된 미만성 기관기관지형 유전분증 1예를 경험하였기에 문헌고찰과 함께 보고하는 바이다.

• Journal of Gastric Cancer
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• 제21권3호
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• pp.258-267
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• 2021

Purpose: As the rate of endoscopic resection for early gastric cancer (EGC) has increased in patients with comorbid diseases, it is necessary to elucidate the efficacy of endoscopic submucosal dissection (ESD) for EGC in patients with comorbidities. This study aimed to analyze the clinical outcomes of ESD for EGC in patients with comorbidities. Materials and Methods: A total of 969 patients with 1,015 lesions who underwent ESD for EGC at Seoul National University Hospital between 2010 and 2014 were analyzed. The short- and long-term clinical outcomes were evaluated according to the comorbidity status. Results: Comorbidities were observed in 558 patients (57.6%). The comorbidity group had a higher proportion of patients using antithrombotic agents (29.5% vs. 0.9%; P<0.0001). Although procedure-related complications (bleeding and perforation) were not significantly different between the two groups, the length of hospital stay was significantly longer (1.8 vs. 1.4 days, P=0.023), while survival was significantly shorter in the comorbidity group (5-year overall survival rate: 90.5% vs. 97.2%, P<0.0001; 5-year disease-specific survival rate: 97.9% vs. 100%, P=0.018; 5-year disease-free survival rate: 83.4% vs. 89.2%, P=0.007). Conclusions: Gastric ESD can be performed in patients with comorbidities without increasing the risk of complications.